Process for preparing a dry compacted detergent composition

ABSTRACT

A SOAP-LIKE COMPACT DTERGENT, CONSISTING OF A MIXTURE OF DRY-COMPACTED POWDER COMPONENTS IS PRODUCED BY MIXING THE COMPONENTS IN THE DRY STATE, MILLING THE MIXTURE AND COMPACTING THE RESULTING POWDER IN DIES WITH A MINIMUM PRESSURE OF ABOUT 30 KG/.CM.2.

OR 3562165 EX US. Cl. 252-99 4 Claims ABSTRACT OF THE DISCLOSURE Asoap-like compact detergent, consisting of a mixture of dry-compactedpowder components is produced by mixing the components in the dry state,milling the mixture and compacting the resulting powder in dies with aminimum pressure of about 30 kg./cm.

The present invention relates to a compact product based on detergentpowder, said product having the shape and compactness of a common soapto be used in fact like a common soap, but which is obtained by a newprocess for this kind of product.

In fact, pieces of hard synthetic detergent presently on the market, areobtained by the conventional soap making process, consisting essentiallyof mixing the various components with water, drawing, refining thepaste, drawing again, cutting and molding.

This process in the manufacture of hard detergents, as those previouslycited, has several shortcomings of an operative, economic andqualitative character. In fact, the working cycle is necessarily verycomplicated and difiicult as the materials entering into the formula ofsaid hard detergents have a nature quite different from those of aconventional soap obtained from fatty acids.

It is also very important to note that the quality of these products isnot entirely satisfactory. The product shows in fact, when used, a nonsmooth and non soft surface. Under the solvent action of the water, whenthe product is used, there will develop a surface showing a certainsandy aspect or roughness which is very unpleasant and which, if thesoap is used as a washing soap can amount to such a degree as to beharmful to the washed fabric, due to abrasive action. Furthermore saidmanufactured products are not very resistent to elevated roomtemperatures, tend to become soft and to exude moisture.

Another disadvantage of the conventional processes results from thelimits to which the formulation is submitted, due to the presence of ahigh water content in said formula preventing the use of substanceswhich are incompatible with one another in the presence of free water.

The working process to which the invention relates (defined for the sakeof shortness as a dry process), ensures remarkable advantages from theoperative, economical and qualitative standpoints.

In fact the simplicity of the technological process, its remarkablequickness and the very limited number of required equipment andmachinery ensures high efficiencies and therefore low manufacturingcosts. The investments in money for purchasing the equipment is far lessthan that required by the above mentioned conventional process. Alsofrom the standpoint of quality, the dry process ensures remarkablyhigher results than those obtained by the conventional process; theroughness of the surfaces of the piece is entirely eliminated. Duringuse a smooth and soft surface, almost like that of a normal soap isretained; the appearance of the piece ob- 3,562,165 Patented Feb. 9,1971 tained by the dry process is more pleasant and finally the obtainedvolume, at a given weight, is greater.

The dry" process also shows a large flexibility of formulation due tothe almost total absence of free water in the composition of theproduct. If the manufactured product is to be used as a washing soap,solid bleaching agents, such as sodium perborate and/or ammonia basecompounds and/ or chlorine base compounds can be added to theformulation without affecting the compound itself.

The process to which the present invention relates will be describedhereinafter:

The components of the formulation are dry mixed in a powder mixingapparatus of any kind. It is fundamentally important to the effect ofthe subsequent operations that the free humidity in the mixture of thepowders be as low as possible, mainly in order not to affect the goodfluency of the powders. The amount of total humidity can also be veryhigh, but said water must be present as crystallization water of one ormore components of the formula and not as free water.

The mixture will then be ground in a powder mill. The grain size of thepowders after milling can range from an impalpable powder to a coarsepowder, and said feature has a remarkable importance on the effects ofthe quality of the product. It has been experimentally found that theroughness of the piece when used depends on the fineness of the groundpowder, the formula of the product and upon the pressure exerted whenthe components are compacted. In other words, certain possiblecomponents of the formula can cause a roughness in the use of thefinished product if they are not ground to an impalpable powder, whileother possible components of the formula can remain in a relativelycoarse form, without thereby affecting the softness of the feel when thet piece is used. It is important to remark that the milling operation ofthe various ingredients can be carried out before the mixing operation,either individually for each component of the formula or for groups ofcomponents.

The mixed and ground powders in the desired proportions are then sentdirectly to a compacting operation without passing through any otherintermediate working stage. It has been in fact found that detergentpowders having determined compositions if-adequately compressed underpressures of at least 30 kg./ square cm., with particular contrivancesin the equipments required for compacting, and provided that saidpowders are ground at a fineness adequate to the particular formulationwhich has to be compacted, give products which can be used like commonsoap, wearing out regularly without foliating or crushing, and beingstable through the entire time of use without undergoing degradationeven in the most unfavorable ambient conditions.

For the compacting operations it is necessary to have a machine equippedfor this purpose, in order to solve the several problems deriving fromthe type of powder (which is very fine and rather sticky) and from theneed of having a powder supply into the dies so as to ensure a constantdosage and therefore a constant weight of the piece, from the need ofoperating always under the same pressure on the powder in order toobtain a piece having uniform characteristics.

It is not essential that the compacting machine used in this process beof any particular kind. Either a die and punch reciprocating machine(for instance of the kind used for compressing thermosetting resins) ora rotary machine (for instance of the kind used for compacting medicinalproducts) or a compounded rotary-reciprocating machine can besuccessfully used. What is essential for the process is a group oftechnical contrivances and equipment as hereinafter described.

The supply of the powder to the die, when effected volumetrically,should be carried out 'by vibrating the powders in order to prevent thelatter from having a variable apparent density depending on the aerationof said powders, the level of the powder in the feeding hopper, and forpreventing bridges from being formed in the dosing device. The above hasa particular importance due to the high amount of powder which must befed into the die.

An example of a suitable kind of supply of the powders consist in aconstant level hopper fed by a rotary valve controlled by an electricmotor. The terminal portion of said hopper has a quadrangular shapedsection and is connected by means of a flexible hose to guides on whichglides a two compartment drawer having an equal volume and aquadrangular section approximately equal to that of the feeding hopper.Said compartments have hinged movable bottoms, the opening or closingmovements of which are controlled by an electromagnet. When one of thecompartments is being loaded in its position under the feeding hopper,its movable bottom is closed, while the other compartment is dischargingin a stroke little hopper, wherefrom the powder directly falls into thedie. The movement of the drawer which glides in the guide connected tothe flexible hose is operated by an electromagnet.

As aforesaid, in order to ensure a constant specific gravity of thepowders contained in the drawer each time, on the drawer itself acontinually operating vibrator is mounted. Thus the powder in the dosingcompartments of the drawer will always settle in the same way, thushaving a constant apparent specific gravity and therefore a constantweight of powder will always be obtained in both dosing devices. If aproduct having a different weight is to be produced, the possibilityexists of course of substituting dosing devices having a differentvolume for the drawer.

Under the drawer a stroke little hopper is mounted, the top crosssectional area is in immediate contact with the drawer and has such anarea as to allow the discharge of the powder into the little hopper,whatever the position of the drawer. As aforesaid, the little hopperfeeds directly the die into which the powder will be compressed.

Of course it is possible to use other feeding devices, of the volumetricor weight type.

Another essentially important point for the successful issue of theoperations is the pre-compacting operation. It is necessary to expelfrom the powder the maximum possible amount of air before the finalcompacting, in order to avoid any included air from remaining in thepiece when large amounts of powder are compressed at high speed, saidair being very harmful since it will cause a great weakening of theproduct, rendering it brittle and friable instead of hard and compact.Further, without adequate pre-compacting it will be very difficult toobtain high manufacturing capacities as the punch of the press wouldhave to effect too long a stroke and consequently the time required forthis operation would be high.

The embodiment of this operation of course differs from one to anotherkind of press. In case of reciprocating presses, the pre-compression canvery simply consist of a change of the stroke speed of the puncheswithin the die; in case of rotary presses, in a gradual and relativelyslow nearing of the upper punches to the lower punches; in case ofcompounded system press, the pre-compression can be obtained by one orboth of the aforesaid systems.

Of course other mechanical systems may be used. What is really essentialis a pre-compacting reducing in a relatively slow way the apparentvolume of the powders by at least 25% and which expels such an amount ofair when the powders are subsequently compressed (carried out at a moreor less high speed), no shortcoming will result from air enclosed withinthe manufactured product.

In case of reciprocatory or compound presses, according to the selectedformulation, it may be necessary to use more than one pre-compactingstation. In other words, it might benecessary to compress the powderssequentially a certain number of times (2 to 6 times) in order to ensurea satisfactory expulsion of the air and an adequate gliding and settlingof the powders themselves in the already partially compacted piece. Thecompacting must be carried out under relatively high pressures, in factpressures of at least 30 kg./square cm. are necessary, in order toobtain a manufactured product having satisfactory features.

It is important to remark that the formulation has a fundamentalimportance in the selection of the pressure to which it is necessary tocompact the powder.

As far as the mechanical part of the operations is concerned, thecompacting operation is carried out in the die (which must be slightlyconical in order to allow the expulsion of the finished product) intowhich the powder has been introduced and precompressed. Two punches(both movable or either movable) operate the actual compacting and givethe shape to the manufactured product.

The pressure can be supplied by mechanical (eccentric presses, togglepresses, etc.) or by pneumatic or hydrostatic means (oleodynamic orhydrodynamic presses).

The manufactured piece can be expelled upward or downward of the die,and the various mechanical systems for embodying said operations arewell known.

Another fundamental operation is that of cleaning the die and thepunches. The powders which are submitted to the operations are rathersticky due to the nature of one or more components of the formulation tobe compacted or due to possible relatively large amounts of free water.

Obviously various mechanical systems can be devised in order to exertthis function, but practically the most efficient system consists incausing rotary brushes to pass, after each compacting cycle, on thepunches or inside the die, said brushes removing any fouling which couldbe left.

Soon afterwards, the lubrification operation has to be carried out andthis operation can be embodied, either by particular kinds of lubricantpowders (for instance talcum, kaolin, starch, silicic acids etc.) whichcreate a very thin film on the surface contacting the detergent powders,or by suitable lubricants (oils, silicone emulsions, water, kerosene,other petroleum derivatives, etc.).

Several devices suitable to carry out said operations exist and are wellknown in the art.

It is interesting to remark that the lubrication can be effectedsimultaneously with the brushing operation, coupling in the mechanicalbrushing devices the lubricating devices.

In order also to avoid difficulty in removing the pieces from thepunches, it may be useful, according to the formulated compound, whichmust be compacted, to cool or to heat the punches or the die, or both.

As far as the formula is concerned, if the product is to be used as awashing soap, the composition of a compact detergent of the typedescribed in the first part of the present invention is very similar tothat of the common sprayed detergents. In said composition are includedsodium aryl-alkyl sulphonates, having variable lengths of chain of thecarbon atoms, complexed sodium phosphates such as sodiumtii-poly-phosphate or pyro-phosphate, optical coloring agents,carboxymethyl cellulose, sodium carbonate, sodium sulphate, ammoniumbicarbonate, waterglass, sodium metasilicate, starch etc.

Due to its compacting assisting action in this type of process, thepresence of waterglass with a ratio Na O:SiO variable from 1.0:1.3 tol.0:1.5, is extremely important.

It is of course possible to obtain manufactured products without the useof this ingredient, but said products have a lower quality than thoseobtained with the waterglass having the characteristics as describedabove, due to a lower cohesion and compactness, due to a greatertendency to crush, to a lower mechanical strength of the product. Thewaterglass in the above Na O to SiO ratios acts in fact as a bindingagent for the whole mass and therefore compacting pressures lower thanthose which would be necessary in the absence of such an ingredient.

The amount of waterglass (with the aforesaid characteristics) necessaryto obtain a product of good quality, of course varies according to theformulation, from 0.5% to 35.0%.

As to the techniques to be used for adding the waterglass solution tothe mixture of powders, avoiding the formation of a pasty mass, it issuflicient to add the solution on an anhydrous or partially hydratedingredient, or a mixture of anhydrous and/or partially hydratedingredients, such as for instance sodium tri-poly-phosphate, sodiumpyrophosphate, the sodium orthophosphate, the sodium carbonate, etc. Itis to be noted that (according to the kind of the components the formulahas) it may be necessary to cool or to heat the mixture of the powderswith the waterglass solution in order to promote and to accelerate thecrystallization process of the free water and of the waterglasssolution. On the other hand, it may be necessary to leave the mixturefor a certain time in order to enable the hydration reaction to reachits completion. Once the hydration of the hydratable compounds iseffected, and a dry powder is obtained, the other powders are normallyadded.

The required waterglass can otherwise already exist in the sodiumaryl-alkyl-sulphonate (or other sulphonate or sulphate) previously mixedin paste form with the solution of waterglass having the aforesaidfeatures, and then dried.

Even without waterglass having the aforesaid characteristics, it ispossible to obtain manufactured products showing satisfactory qualities.It is however necessary to adopt remarkably higher compacting pressures.

As already pointed out, particular components with bleaching andcleaning properties can be used; without the risk of decompositionduring the manufacturing process and during the storage of the piecesbefore their sale and use.

In connection with these materials, it is to be noted that the ammoniumbicarbonate, when contacted with water, inhighly alkaline media, formsammonia, which, as is known, has a bleaching power; that the sodiumperborate, in contact with water, releases active oxygen, having ableaching and cleaning power; that the chlorinated substances, such ascalcium and lithium hypochlorite, the di-chloro and tri-chloro isocyanuric acids, or also mixed or not, their alkaline and/or alkalineearth metal salts, when contacting water, release active chlorine havingcleaning and bleaching power.

Said materials cannot be used in the normal sprayed detergents or in thecompact detergents manufactured by the conventional processes, becausethe development of ammonia and/or of oxygen and/or of chlorine duringthe manufacturing process would occur due to the presence of water.

In the dry" process according to the present invention, said ingredientscan be used without risk of decomposition during the manufacturingprocess or during the storage. The decomposition occurs, on thecontrary, when the compact detergents are used, i.e. when the usercontacts the compact detergent containing one or more of the aforesaidsubstances with the fabric to be washed and the water. The developmentof ammonia and/or of oxygen and/or of chlorine occurs in the mostfavorable conditions, both from the physical-chemical point of view aswell as from the point of view of performance, as the developing ofammonia and/or of oxygen, and/or the chlorine are directly contacting,in high concentration, the fabric to be washed.

It is however to be noted that the aforesaid substances do notnecessarily have to form part of the detergent composition, for the drymanufacture of the compact deterge'nt. It is quite possible to provide aformulation wherein the above mentioned substances do not exist at all,although all advantages deriving from the process remain valid.

Some examples of formulations are ported:

hereinafter re- EXAMPLE NO. 1

The following substances, in the amounts and in the order as indicated,are put in a common powder mixer:

10 parts of sodium tri-poly-phosphate 10 parts of sodium carbonate 10parts of waterglass, in 30% solution The mixture is heated, cooled; thenadded with:

The mixer is started and operated for about minutes.

The mixture of the powders is discharged into the feeding hopper of ahammer-type mill. The mill is fitted with sieves suitable to obtain amaximum grain size of 100 mesh is started.

The powder thus milled is pounded into the feeding hopper of the dosinggroup of the compacting machine.

The dosing group is pre-set for dosages of 250 grams, with dosingallowable variations of :5 grams.

The compacting machine is started, feeding the lubricating devices ofthe dies and of the molds with a mixture, in equal parts of ventilatedtalcum and silica gel.

The dosed powder, poured into the lubricated dies, is de-aerated bycompression and then definitely compacted in the actual compactingstation under a 155 kg./sq. cm.

pressure.

The compacted piece will be expelled in the subsequent station and sentto a packaging station.

EXAMPLE NO. 2

The following substances, in the amount and in the order as hereinafterdisclosed, are put in a common powder mixer:

parts of sodium tri-poly-phosphate 5 parts of sodium carbonate 5 partsof ammonium bicarbonate 14.7 parts of sodium sulphate 10 parts of sodiumbentonite (white 350 gel) parts of sodium alkyl-benzene-sulphonatemixture with 10% waterglass 0.2 part of perfume 0.1 part of opticalbleaching agent The mixer is started and then operated for about 25minutes.

The mixture of powders is discharged into the feeding hopper of thehammer mill. The mill fitted with suitable sieves in order to obtain agrain size of 120 mesh is started.

parts of the mixture thus obtained and 10 parts of the mixture follows:

98 parts of potassium-di-chloro-iso-cyanurate 2 parts of silica gel areintroduced into a common powder mixer and mixed for about 5 minutes.

The so mixed powder is transferred to the feeding powder of the dosinggroup of the compacting machine.

The dosing group is pre-set for dosages of 400 grams, with allowablevariations of i8 grams.

The compacting machine is started, supplying the lubricating devices ofthe dies and of the molds with a mixture in equal parts of fluidvaseline oil and of fluid silicone.

The dosed powder, poured in the lubricated dies, will be deaerated bycompression and then finally compacted in the actual compacting stationunder a 180 kg./sq. cm. pressure.

The compacted piece will be expelled in the subsequent station and sentto a packaging station.

If the product is to be used as a toilet soap, of course the compositionof the possible formulations will be different, even if themanufacturing process remains identical to that described in the firstpart of the present invention.

In said compositions there will be ingredients well known in thetechniques of toilet soap and cosmetic art, such as for instance sodiumlauryl-sulphate, sulphates from animal or vegetable fats,alkyl-aryl-sulphonates, as detergents particularly suitable for theskin, fatting agents as for instance lanolin or vaseline, foamingagents, such as for instance the ethoxylated or non-ethoxylated fatamides, ingredients for imparting a particular plasticity to thefinished piece such as for instance talcum or silica gel, waterglasshaving the features similar to those previously cited in connection withthe manufactured product for washing purposes, and finally eccipients,coloring agents, and perfume.

A remarkable advantage of these kinds of soap is the possibility ofobtaining a product which, when in solution, can have a neutral pH or anacid pH thus showing a beneficial effect on the skin which normally hasan acid pH. This is possible as the above cited detergents (as generallyalmost all synthetic detergents) are stable in acid medium, as opposedto the behavior of common soap from fatty acids which is unstable inacid medium.

In order to obtain a neutral or acid pH, an organic acid can be added tothe formulation, such as for instance citric acid and/or tartaric acidand/or oxalic acid; or it is possible to use a buffer system such as forinstance a mixture of monosodic and bisodic phosphates, or buffermixtures of other well known complexed phosphates. Of course also otherbuffer systems can be used, provided they are compatible with the othercomponents of the formulation.

As to the use of the waterglass previously discussed, the same criteriaapply as with the product for washing purposes.

Hereinafter will be disclosed an example of formulation of a compactdetergent for use as a toilet soap.

EXAMPLE NO. 3

To a common powder mixer the following substances are charged in theamounts and in the order as hereinafter disclosed:

parts of a 30% solution of waterglass are added to a mixture of- 10parts of anhydrous monosodic sodium phosphate parts of anhydrous sodiumsulphate the mass is mixed until complete crystallization of thesolution water of the waterglass is obtained.

Then are added:

parts of sodiumlaurylsulphate in 80% powder 8 parts of maize starch 5parts of cocomonoethanolamide 5 parts of talcum 1 part of citric acid 1part of perfume The dosed powder, poured into the lubricated dies, willbe deaerated by compression and then finally compacted in the actualcompacting station under a pressure of kg./sq. cm.

The compacted piece is expelled in the subsequent station and sent to apackaging station.

It is evident that in both cases of the washing soap and of thetoilet-soap, other examples might be cited. Those skilled in the art mayprovide for changes and variations of the formulations for thosesubstances covered hereby without departing from the principles andspirit of the invention.

By the above described process it is also possible to obtainmanufactured products where particular ingredients are present havingdifferent colors from the color of the powder, in order to evidence thepresence of said ingredient to the consumer.

It is for instance possible to obtain a manufactured product having anycolor in the mass of which are more or less uniformly distributed blueor green or yellow colored grains, or having any other color, saidgrains having an equal or different composition with respect of theremainder of the manufactured product.

These grains can be obtained by means of the well known dry or wet grainmaking processes and can have any detergent and/or bleaching and/orcleaning composition, previously mixed with a coloring agent.

Also other systems may be used, but regardless of how said coloredgrains are obtained, they must be mixed in a common mixer for powders,before compacting, with the ground detergent composition.

Having thus disclosed the invention, what is claimed is:

1. A process for preparing a dry, compacted detergent composition, saidprocess comprising dry mixing the components of the detergentcomposition which are:

(a) from 0.5 to 35.0% of waterglass, wherein the ratio of Na O to Si0 isbetween 1.0:l.3 and 1.0:1.5; and

(b) at least one member of the group consisting of sodiumtri-polyphosphate, sodium pyrophosphate, sodium orthophosphate, thesodium acid salts thereof, sodium carbonate, sodium sulphate, neutralsodium borate and acid sodium borate;

grinding the resulting mixture, deaerating the ground mixture to reducethe apparent volume of same by at least 25% and compacting same in amold under a pressure of at least about 30 kg./sq. cm.

2. A process as claimed in claim 1 wherein the detergent compositionfurther contains ammonium bicarbonate.

3. A process as claimed in claim 1 wherein the detergent compositionfurther contains at least one member of the group consisting of sodiumperborate and sodium percarbonate.

4. A process as claimed in claim 1 wherein the detergent compositionfurther contains at least one member of the group consisting ofdichloroisocyanuric acid, trichloroisocyanuric acid, alkaline earthmetal salts thereof, lithium hypochlorite and calcium hypochlorite.

References Cited UNITED STATES PATENTS 2,607,738 8/1952 Hardy 252-1022,801,978 8/1957 Perlman 252-137 2,979,464 4/1961 Pistor 252-993,247,122 4/1966 Schaafsan et a1. 252-174X 3,329,615 7/1967 Cooper et al252-99 MAYER WEINBLA'IT, Primary Examiner US. Cl. X.R.

